Process of preserving.



G. W. LUHRMANN 61 R. MAGRANE.

PROCESS OF PRESERVING.

APPLICATION r1151) MAR. 10, 1915.

Patented May 23,1916.

1 UNITED STATES PATENT OFFICE.

GEORGE W. LUHRMANN, 0F JERSEY CITY, NEW JERSEY, AND; ROBERT MAGRANE, OF NEW YORK, Y., ASSIGNORS TO ANCHOR CA]? & CLOSURE CORPORATION, OF BROOKLYN, NEW YORK, A CORPORATION OF NEW YORK.

PROCESS OF 'PRESERVING.

To all whom it may concern Be it known that we, GEORGE W. LUHR- MANN and'RoBERT MAGRANE, citizens of the United States, and respectively residing at Jersey City, in the county of Hudson and State'of New Jersey, and at New vYork, in the county of Queens and State of New York, have jointly'invented new and useful Improvements in Processes of Preserving, of which the following is a specification.

This invention relates to methods for preservin food and the like, and has particular re erence to the processing of foodstufl's in glassreceptacles or other forms of sealed containers.

The objects of invention include a method adapted to process goods at a low cost and in glass containers, to secure a better product with less impairment of flavor and-\vlth greater keeping qualities, and t0 reduce the lossesof containers and goods that occur in processing.

Referring. to the" drawings: Figures 1, 2 and 3 represent sectional elevations of typi cal forms of glass containers in .which are packed the material to be processed; and

, Fig. 4 isa sectional elevation, partly dia-v grammatic, ofa process kettle and its various attachments which are of use in carrying out the improved method.

In the usual method ofprocessing food the containers are provided with a vent,

which is sealed'after the goods are processed' In some cases the containersare first sealed, and are placed in a process kettle or retort where they are subjected to the action of, heat supplied directly or indirectly by i heated water or steam. The temperature and the length of time the processing is carried on depend upon the character of the food to be sterilized, also to some extent 7 upon the size and character of the container.

- pounds, steam gage) and the resulting tem- Ina typical case, the processing of meat or fish, by diqfact steam heat, the containers.

are subject. to

he heat of saturated steam at a pressure of about 25 po'iindsabsolute (1O perature at this pressure is about 240 degrees F. The time of, processing for a ten ounce container is one hour.

'If the heat. be unnecessarily high, or

Specification of Letters Batent.

Application filed March 10,

Patented May 23, 1916. 1915. Serial No. 13,517.

maintained for too long a time, theflavor of the foodstuff is greatly injured, and it is desirable that the food be processed at the lowest temperature and in the shortest space of time that will effectively preserve the goods.

Furthermore, to process food under the best conditions so that the flavor will be im-. paired as little as possible and so that the food itself will keep Without spoiling for long periods of time, it isdesirable that the goods be packed in glass containers in preference to tin, and the food should also be kept from contact with oxygen or air during and after the sterilization to eliminate oxidation and discoloration of the food at the comparatively high sterilizing temperatures, and during the comparatively long time the goods are kept before they are used. In the improved method herein disclosed, this oxidation and discoloration.- which occurs during and after processing is checked or prevented by sealing the container under a vacuum before it is placed in the retort. The container ispreferably made of glass,

.as indicated at 10 in Figs. 1, 2 and 3, and is tainers are then placed in the retort andsubjected to the processing heat. I

In processing with'steam under pressure, the temperature and the pressure of the steam (saturated) have a mutual relation in accordance with well known laws, the pressure and the temperature increasing and decreasing together in definite steps so that any given temperature has a definite related pressure and vice versa. As in the case cited above, the fact that saturated steam is under tenpounds gage pressure indicates also that its temperature is 240 degrees F. Repeated experiments .have shown, however, that the temperature andpressure values of the foodstuffs within the container do not vary in. like proportion to steam, and that when such nally will material is heated in a confined space such as the sealed container, the pressure, generated within the container is much greater in proportion to the temperature than is the case with the saturated steam outside of the container. This difference is very marked in practice.

If a container be filled with sealed hermetically under a vacuum,'it' may then have an internal pressure of about one pound absolute per-sq. in. If it be placed 1n a retort having live steam at a tempera ture of 240 degrees F., the pressure outside of the container and acting upon it exterbe about pounds absolute per sq. m. As the contents of the container become heated, however, the pressure will rise rapidly so that when the contents reach the temperature of the steam (240-F.) the container may have an internal pressure of about 45 pounds absolute per sq. in., is subject to a burstin sq. in. and may elther blow out or blow up. For this reason, the processin of food'm sealed cans or glass is more di cult than in the case of vented cans. The glass container, in particular, and its closure cannot be seamed and doubleseamed together as in the case of the tin can, and it cannot withstand as much internal pressure. Attempts to remedy this trouble by applying temporary clamps to the closures during processing have been unsuccessful, When the clo-' sure is thus clamped on, or when it is held in place by a locking shoulder on the glass as shown in Fig. 3, the internal pressure is sufficient in many cases to blow out the gasket I nearby.

or to rupture it at some point and the contents of the containerv escape through the break in the gasket, spoiling that particular container and soiling all the others that are Attempts have alsobeen made in processmg to create a counteror su' ersteam pressure outside of the containers y compressed a1r so that the external pressure will always be greater than the internal pressure.

I These attempts have been only partially suc cessful as the air was not also withdrawn from the container b' ore sealing so that there was an excessiv pressure inside the container and an unnecessarily greater pressure had to be maintained outside of the container. The presence of the air within the container also operated to oxidize the food during the sterilization, resulting in more or less discoloration of the product and a lessening ofthe food-value of the product.

" package In carrying out our improved method, we pack the food material in the container an seal the container-with its closure after ex- 'hausting the air therefrom. The sealed exhausted of air is then placed in the process kettle where it is subjected to a suitable processing heat such as that ,de-'

strain of 20 pounds per' d being that at rived .from live steam and at the same time to an external pressure such as caused by the steam and heated compres'sedair, the pressure outside the container being such as to exceed the pressure' generated within it.

by admission of compressed air, preferably f preheated, through inlet 17 A rose 18 supplies water for cooling purposes- A steam gage is indicated at 19, .a safety valve at 20, a thermometer at 21 and a blow-off cock at 22.

In the case of-processing meat cited above, the temperature in the retort is maintained at 240 degrees F, while the pressure is kept at about 30 pounds (steam gage) or 20 pounds more than the pressure of saturated steam at 240 F. Under these conditions meat can be packed in glass containers such as that shown in Fig. lwhere the closure is held in place only by atmospheric pressure.

By packing the goods, preferably in glass, in a vacuum, and applying the processing heat and supersteam pressure to the package 'so formed, as described above, it has been possible to preserve foodstuffs to the best advantage,' it being possible to process the food at the minimum temperatures and pressures, thereby preserving the food value and the flavor to the greatest possible extent.

A further advantage inthe use of glass h sterilizing tempart of the present invention. The superpressure is a fluidpressure which may be transmitted by or by water or any given temperature, its pressure is greater than the pressure of saturated steam at the given' temperature. 1

compressed air or other gas, other fluid, its characteristic It is obvious-that many modlfications may be made in the improved methodofpreserving herein disclosed and the invention is not limited in its breadth and scope to the particular means herein shown and described.

We claim: 1. The method of preservin food which consists inpacking the material in a'container, sealing the container under a vacuum,

subjecting the container and contents to a sterilizing heat, allowing them tolcool, and. maintaining meanwhile, during the heating and cooling operations, an exterior fluid pressure upon the container that is in excess of the pressure within the container.

2. The method of preserving food which consists in packing the material in a glass container, sealing a closure to the container under a vacuum, subjectmg the sealed container and contents to a sterilizing heat, al-

. lowing them to cool, and maintaining meanwhile, during the heating and cooling opera 4. The method of preserving food which includes the packing of material in a container, sealing .the container under a vacuum, subjecting the container and contents to a sterilizing" temperature for an effective period and to a fluid pressure that is in excess of the pressure of saturated steam at the given temperature.

5. The method of preserving food which includes the packing of material in a container, sealing the container under a vacuum,

and then subjecting the container and ma.- 1

terial to a sterilizing heat and a fluid pressure that is in excess of the pressure inside the container.

6. The method of preserving food which includes the packing of material in a glass container, sealing the container under a vacuum, subjecting the container and contents to the. heatingaction of live steam under pressure in contact with the container, and-maintaining an exterior pressure of the steam used to supply the hea 7. The method of preserving food which consists in packing the material in a glass container, sealing the container under a vacuum, subjecting the container directly-to f the action of steam at a sterilizing temperature for a required period, and at the same time to an external pressure of gassuch as compressed air which has a greater pressure than the pressure of the steam at the sterilizing temperature, cooling the container by water, and maintaining the said external pressure of gas during thecooling.

GEORGE W. LUHRMANN.

ROBERT MAGRANE.

Witnesses:

DAVID Coma, J. R. STEWART. 

